Hollow metal ball and method of making same



Oct. 31, 1939. K. KNUDSEN 2,177,928

HOLLOW METAL BALL AND METHOD OF MAKING SAME Filed Dec. 9, 1936 sSheets-Sheet 1 INVENTOR fiw/p KvupstW BY Q 7% ATTORNEY Oct. 31, 1939. K.KNUDSEN 7 3 HOLLOW METAL BALL AND METHOD OF MAKING SAME Filed Dec. 9,1936. 3 Sheets-Sheet 2 mm -TW ATTORNEY K. KNUDSEN Oct. 31, 1939.

HOLLOW METAL BALL AND METHOD OF MAKING SAME Filed Dec. 9, 1936 3Sheets-Sheet 3 ATTO R N EY tented I H I .r

- UNITED STATES PATENT OFFICE I V Knud Knudsen, Danbury, Oonnq' asaignorto Danbury-Knudsen, Incorporated, a corporation of ConnecticutApplication December 9, 1936, Serial No. 115,003 18 Claims. (01'.29-148.!)

This invention is in hollow metal balls and the arrangements of partsand in the several steps method for making them. and relation and orderof each of the same to one One of the objects of this invention is topro or more of the others, all as will be illustratively vide a low costprecision hollow metal ball having described herein, and the scope ofthe application certain relatively precise or narrow limits of ratio ofwhich will be indicated in the following claims. 5 of its weight to itsvolume particularly with re- In the accompanying drawings, in which arespect to the specific gravities of alcoholic liquors shown certain ofthe preferred forms or embodiof which whiskey, gin, and the like, mayserve as ments of certain mechanical features of my inexamples, andhaving also adequate resistance to vention, 1 attack thereon by suchliquors or constituents in Figure 1 is a vertical sectional view of anappaor of the latter. Another object is to provide a ratus for achievinga step in the earlier stages ball of the above-mentioned character andcapa of making of the hollow ball;

ble of inexpensive and quantity-rate of produce Figure 2 is a similarview of another apparatus tion and yet maintain and provide aconsistency for achieving a succeeding step; or uniformity of roundnessto insure dependable Figure 3 is a horizontal sectional view as seen 18coaction with a ring-like or annular valve seat, along the line'33 ofFigure 2;

usually of cork or like composition, for dependable Figure 4 is aperspective view of a half-ball repassage-sealing action at all timesand of a disulting from such steps as those typified in Figminutivenessappropriate for incorporation into ures 1, 2 and 3;

certain types of non-refillable so-called stoppers Figure 5 is a planview of a ring member in an 30 applicable to the necks of bottles.Another obearly stage; ject is to provide a thoroughly practical methodFigure 6 is a vertical sectional view of an appaand apparatus forproducing balls of the aboveratus for operating from the ring member ofFigmentioned character, capable of achieving a cost ure 5;

of production so low as to make it possible to Figure 7 is an explodedperspective view 01' 25 fit balls of this character and the bottlefitment three parts that go to make up the hollow ball or stopper withwhich the ball is to coact for nonstructure as they appear just prior topreliminary refillable action, into the small margin of cost assembly;available therefor to the distiller or bottler of Figure 8 is a.sectional view through the assemliquors and the like or to otherproducers and blage resulting from the parts shown in Figure 30 bottlersof liquids. Another object is to provide 7, the section being takenthrough the axis of a method and apparatus for the production of theabove-mentioned ring member;

balls of the above-mentioned character that will Figure 9 is a sectionalview of an apparatus be eificient, reliable in operation, capable ofhigh for applying soldering flux to certain parts of the rate ofproduction, and well adapted to meetthe hollow ball structure; 35varying requirements of practical manufacture, Figures 10 and 11 arefront elevations, respecand particularly the requirement of low cost oftively, of possible forms of apparatus for accomproduction. Anotherobject is to provide ahollow plishing the step of actual solderingtogether of ball construction meeting such requirements as the severalball parts;

those noted above and which, nevertheless, will Figure 12 is a frontelevation partly in section 40 be strong, durable, uniformly round, ofadequateof an apparatus for forming a succeeding step in ly uniformdistribution of weight, and of adethe ball production; quately uniformcapacity or tendency to roll. Figure 13 is a front elevation partly insection Another object, is to provide a method and appaof the ballconstruction as it appears upon the ratus for the quantity production ofballs of the conclusion of the step shown in Figure 12, and 45above-mentioned character and capable of Figure 14 is an elevationpartly in section of achieving such uniformity of the above-menthecompleted and final ball structure, after the tioned characteristics ofthe ball as to minimize conclusion'of certain succeeding steps. greatly,if not entirely eliminate, the need for Similar reference charactersrefer to similar testing of the balls, particularlyfor such qualitiesparts throughout the several views of the drawas ieak-proofness,buoyancy, ratio of weight to ings. volume, and the like. Other objectswill be in As has already been indicated above, the holpart obvious orin part pointed out hereinafter. low ball, to function in certain typesof non- The invention accordingly consists in the fearefillablestoppers, particularly for liquor bottures of construction, combinationsof elements, ties, has to meet certain peculiar requirements not theleast of which is low cost of materials employed and low cost ofproduction; at the same time it must expose to the liquor or liquid aconstituent which is not soluble in liquid or in constituents of thelatter and is not attacked thereby, and in certain instances it mustmeet, within a relatively narrow margin, a certain requirement as toratio of its weight to its volume. In these latter instances, such ratiois important as it bears upon the degree of presence or absence ofbuoyancy of the hollow ball and in some instances also the ball has tocoact with or isacted upon by a movable or weighted member, therelationship of whose weight, at various angles of tilting of thebottle, to the weight and degree of buoyancy of the hollow ball are sometimes of major significance in the functioning of that type ofnon-refillable stopper. For illustrative purposes, it will sufflce tostate that, even in the most exacting of such instances such as thoselast-mentioned, this ratio is met if the final ball is of an outsidediameter of 0.500 inch, with a tolerance of 0.001 inch, and its weightis between 13.5 and 15.0 grains; a ball meeting these last-mentionednumerical specifications functions satisfactorily in a non-refillablestopper for use with alcoholic liquors, such as whiskey, gin, or thelike, and causes co-acting parts, such as a tiltable or movable weight,in the stopper mechanism also to ccact satisfactorily. If the exposedsurface of the ball is tin of suitable depth, the requirements ofavoiding contamination of the liquor or liquid are satisfactorily metwith.

However, a major factor in the provision of a hollow ball of thischaracter is the item of cost to the distiller or bottler of liquor andin this item of cost the two principal factors are cost of materials andcost of production. While the parts of the non-refillable stopper orbottle fitment, other than the ball, may be capable of commercialconstruction within a satisfactory price or cost range to permit ofeconomical adaptation of non-refillable stopper into liquor bottles, yetthe cost of commercially producing a hollow metal ball has heretoforebeen so high as to make prohibitive the adoption commercially of suchnon-refillable stoppers by distillers and bottlers of alcoholic liquors.One of the dominant aims of this invention is to overcome this obstacleor prohibition and to provide a hollow metal ball construction and amethod and apparatus for making it of such low cost as to bring not onlythe hollow ball itself but the entire nonrefillable stopper or bottlefitment within the small or narrow range necessary for adoption in theliquor industry.

In the following description, it is assumed, for purposes ofillustration, that the hollow ball to be produced meets all of thevarious requirements and characteristics, some of which have been notedabove, if its outside diameter is 0.500 inch (with the toleranceabove-mentioned) and its weight is between 13.5 and 15 grains, but it isto be understood that the ratio of weight to volume may and can bechanged or departed from, depending upon the particular dimensions,characteristics of the liquor, and other factors, met with or requiredin a non-refillable stopper embodying a hollow metal ball. For theproduction of the ball illustratively dimensioned and weighted as aboveset forth, I prefer to start with a sheet metal such as phosphor bronzeor drawn copper, having an initial thickness of 0.0075 inch. Other sheetmetals may, of course, be employed, having due regard to their densitiesor specific gravities, but in the illustrative example I prefer phosphorbronze or drawn copper because these have sufllcient ductility orworkability and yet are hard enough to resist denting of the final ballin the course of the ordinary production handling thereof. 1

From the sheet metal a disk of appropriate diameter is first stampedout, the diameter being adequate for the subsequent drawing of the diskor blank into a hollow hemisphere. In Figure 1 is shown an illustrativestep of so stamping and then drawing the circular blank.

An upper die member 20 has a recess 2i that is a true segment of asphere having a radius of 0.500 inch but it is preferably of a depththat is a few thousandths of an inch less than that radius, for apurpose later described. The die recess 2| is, therefore, in volume,slightly less than a hemisphere. Member 20 is cylindrical, and enters acompanion die member 22 having a cylindrical hole 22, thus cutting adisk out of sheet metal interposed therebetween, the disk beingperipherally gripped between die 20 and an annular part 23 normally heldwith its upper face in the plane of the face of fixed member 22 by ayielding part such as a rubber collar 23. Parts 23 and 20, with the diskgripped therebetween, now move downward as a unit.

Fixed against movement, as on a pillar 25 is a die part 23 along whichthe member 23 slides downwardly and whose upper portion 23 is trulyhemispherical but of a radius less than that of the recess 2| bysubstantially the thickness of the sheet metal operated upon and whoseuppermostpoint is in or just beneath the plane of the face of the fixeddie part 22. As parts 20 and 23, with the disk or blank heldtherebetween move downward ,as a unit, fixed die part 23 enters the dierecess 2| and correspondingly and progressively trues and shapes theblank or disk into a substantially hemispherical part 24 having,however, a laterally and peripherally extending flange 25 about itsupper or open end.

That step or operation completed, the part 24 is ejected, as by aknock-out member 20 acting after the parts are returned to normal anddie member 20 appropriately elevated, and is now inserted into a recess26, substantially like the recess 2|, of another lower die member 21.Coacting with the latter are two devices; one of these devices is aholding or center or alining member 28, substantially hemispherical, anddimensioned snugly to enter the drawn sheet metal part 24, and to pressand bottom the latter, and securely hold it, in the die recess 26.Member 28 may have a shank or stem 29 extending upwardly where it isconnected to and operated by any suitable mechanism.

The other of the devices comprises a shearing tool 30, in the form of anannulus, as shown in Figures 2 and 3; this cutting tool extends aboutthe stem 29 (Figures 2 and 3) and any suitable means may be provided formounting and moving it radially in an appropriate path or paths orsteps.

Its lower and outer cutting edge or lower face is in the same horizontalplane that is coincident with the plane horizontal upper face of thelower die member 21 of Figure 2. It is shaped, moreover, to fall withinthat portion of the sheet metal part 24 (see Figure 2) that projectsabove the upper face of the die member 21 and it is caused to moveradially outwardly just after the member 28 comes to rest to positionand hold the sheet metal part 24 in proper position.

. and they are, moreover, truly concentric.

As it is made to move outwardly radially (see- Flgure 3) it shears off,along the above-mentioned horizontal plane, the excess metal of thesheet metal part 24, and, moreover, does so, due to the above actions,in a manner to leave a smooth, fiat edge face 3| (see Figure 4) in whatis now substantially a half-ball, the part 24. This edge face 3| issmooth and accurately falls within a single plane, due not only to thesecure holding and alining of the sheet metal part 24 by the coactingparts 28 and 21 of Figure 3, but also due to the progressively andperipherally advancing shearing action as the shearing tool 34 is movedin appropriate steps or paths radially of the axis of the stem 29.

The half-ball 24 of Figure 4 is preferably a true segment of a spherethat is slightly less than a complete hemisphere, but hollow. For eachball to be made, two such hollow half-balls 24 are employed.

Next I make up a joining and alining ring member, one for each ultimateball. This ring member is preferably made of wire, illustratively copperwire of a'thickness of 0.040 inch, and I may make it by winding suchwire in a close helix, and then severing or cutting the helix along aline to form as many split wire rings as there are turns in the helix.One such split ring is shown at 35 in Figure 5. It is of an insidediameter slightly less than the inside diameter of the half-balls 24,and it is shaped as by appropriately formed companion die members 36 and31 (Figure 6) into what may be termed, as above noted, an alining andjoining ring member 38. Illustratively, the die members 33, 31 areshaped to press or stamp the round wire split ring 35 of Figure 5 intothis ring member am) give it a truly cylindrical inner part but whichexternally may be a spherical segment 39 and preferably it hasprojecting laterally from its middle portion a flange 40. The

upper and lower parts 4| and. 42 of the cylindrical part 33 areexternally truly cylindrical or spherical and of a diameter, determinedby the die members 35, 31, substantially equal to the inside diameter ofthe upper open ends of the half-balls 24, one of which is shown inFigure 4, Or the outer surfaces of the parts 4| and 42 may be madesegments of a sphere whose radius is equal to that of the inside radiusof the half-balls or shells. Preferably, also, the free portions, suchas the upper and lower peripheral portions of the parts 4| and 42, asseen in Figure 6, may be made relatively yielding, as by making them oflesser thickness, to better and more easily conform, if necessary, tothe curvatures of the inside faces of the half-balls. The laterallyprojecting flange 40 may be of a thickness of several thousandths of aninch, such as 0.002 or 0.005 inch, and it is by half of that amount, aswill now be clear, that the half-balls 24 fall shy of being true hollowhemispheres.

The alining and securing ring 33 is now given a coating of tin,preferably by electro-deposition, in order thereby to better achieve anicety or uniformity of distribution throughout its surfaces of the tin.This coating of the tin is of sufflcient thickness to provide enough tinfor ultimately soldering the two half-balls to the securing member 33.

In Figure 7 I have shown in exploded perspective two half-balls 24 withan interposed tin-coated flanged securing and alining ring 38, and thesethree parts are now mechanically assembled or interfitted in anysuitable way. Thus,

the upper cylindrical flange 4| is received snugly inside of the uppershell or half-ball 24 and the lower cylindrical flange 42 is snuglyreceived into the open end of the lower shell or half-ball 24, anysuitable means being employed to press the three parts together to makesure that the .plane face edge faces 3| of the half-balls 24 snugly matewith the laterally projecting flange 40 of the ring member 38.

In Figure 8 the resultant assemblage is shown in transverse section andit will be noted that the concentricity of the upper and lowercylindrical flanges 4|, 42 insures that the upper and lower shells orhalf-balls 24 have their axes brought into coincidence. It will also benoted that the flange 40 projects laterally about the equator of theresultantv assemblage.

Thereafter I apply a suitable soldering flux in a position to coact withthe tin of the assemblyring 33 and the contiguous surfaces of the twoshells 24, 24; This I may achieve by causing the assemblage to berolled, by gravity orotherwise, along tracks or guide rails 44, betweenand underneath which is a trough or receptacle 45 containing thesoldering flux 46, preferably liquid, the parts being so dimensioned andrelated that, as the ball assemblage moves along the tracks 44, theprojecting flange 40 has all its portions progressively brought anddipped into the flux 40. In this manner a quick application anddistribution of the soldering flux may be achieved.

Having completed the application of the soldering flux, and bearing inmind that the preferred method of applying the solder comprises, asearlier stated, the application, as by plating, of a coating of tin tothe ring 48, I next proceed to cause a flowing of the tin and this I doby appropriate heating of the parts, two illustrative methods and meansbeing indicated in the drawings for this purpose.

Accordingly, referring first to Figure 10, I have there indicated asuitable frame 41 having two pillars or posts 48, 49 provided withsuitable bearings for rotatably supporting shafts 50 and 5|,respectively. Shaft 50 may be held against axial movement in anysuitable manner and is provided with any suitable means such as a beltand pulley, indicated at 52, for effecting a suitable rate, preferably alow rate, of rotation of the shaft 50 and hence of a cup-shaped holderor chuck 53 rigidly mounted upon the inner end of the shaft.

The other shaft 5|, coaxial with shaft 50, is also provided with acup-shaped holder or chuck 54, juxtaposed to the chuck 53, but shaft 5|is slidable in the bearing in the post 49. Moreover, it is provided witha spring 55 interposed between the post 49 and the chuck 54 and acts toyieldingly thrust and hold the shaft 5| and the chuck 54 in a directiontoward the left. The outer end of the shaft 5| may be provided with asuitable handle 56 or any other appropriate means for periodicallyshifting the position of .the chuck 54 toward and away from the chuck53.

The two chucks, at their contiguous faces, are hollowed out or concavedwith a radius equal substantially to that of the ball assembly. Uponwithdrawing chuck 54 a ball assembly may be positioned between the twochucks, manually or otherwise, with the plane of the ring member 38extending substantially at right angles to the coincident axes of thetwo chucks, the ball assembly being gripped between the chucks under thespring action 55 when chuck 54 is released and being rotated due to thedrive of the chuck 53.

At one or more points, preferably in the plane of the ring member 38, ispositioned a heater, illustratively taking the form of a gas or Bunsenburner liL'with its frame or point of heat emission positioned inappropriate proximity to the rotating equator portion of the ballassembly. Thereby the equatorial portions of the assemblage are heatedto a sufllcient degree to cause a flow of the previously applied tin orsolder, and as soon as such flow or fusion has taken place, theapplication of the heat is withdrawn or the ball assemblage removed fromthe apparatus, whence cooling at any suitable or desired rate may beeffected to complete the union of the three parts 24 3824 (see Figures'7 and 8), the soldering flux previously applied insuring uniform anddependable action of the solder with the adjacent contacting surfaces ofthe half-balls 2424.

Or, turning now to Figure 11, I may provide two concaved or cup-shapedelectrodes 60 and GI pref-- erably with their axes coincident andextending vertical and insulatingly mounted in any suitable way (notshown) in any, suitable frame (not shown). They may be connected as byconductors 62 and 63 to a suitable source of potential, illustrativelyindicated in the drawings as a transformer 64.

Any suitable means may be provided for bringing about a manual orperiodic separation and approach of the electrodes 60 and 6 I; forexample, the lower electrode 6| may be stationary while the upperelectrode Ellmay be mounted for movement along its axis, a lever 65 orlike mechanism having a suitable connecttion with the shank of theelectrode 60 to control up and down movement of the latter. Also, andpreferably, movement of the electrode 60 toward the electrode 6|, underthe control of the lever 65, is brought about through an interposedspring 66.

Accordingly, after the step of applying soldering flux, the electrodes60, 6| are separated to receive therebetween a ball assembly with theplane of the ring member 38 extending at right angles to the coincidentaxes of the electrodes, the latter having preferably a concavity of aradius equal to the radius of the half-ball members 24, 24 in order tomake a good and large surface contact therebetween.

With a ball assembly thus positioned between the two electrodes and thelever 65 pressed downwardly so that its pressure is exerted through thespring 66, energy from the source of potential 64 begins to flow in thecircuit which is closed because of the bridging of the electrodes 60, 6!by the ball assembly. The resultant current flow effects a heating ofthe ball assembly but, because of the smaller and possibly initiallyless perfect surface contacts at the ring member 34 and peripheral endsor edges of the half-balls 24, 24, the resultant greater resistanceachieves a concentration of the heating effect of the current largelythroughout this equatorial region of the assemblage.

A fusion or flow of the tin or solder results accompanied by a uniformflow or distribution of it throughout the adjacent surfaces of the threeparts and a good union results. The circuit may be interrupted to bringabout a cessation of heat production or the ball assembly may be removedfrom the circuit or electrodes, to allow cooling and hence "freezing ofthe solder to take place.

In either of these methods and apparatuses for effecting the soldering,a dependable and proper union of the previously geometrically anddimensionally accurate parts is achieved, for the fiat or plane endedges 3| of the half-balls 24 mate with or rest snugly and flatlyagainst the respective faces of the flange 40 of the ring member I. Thislatter action is insured by the pressure with which the parts arepressed toward each other during the soldering action, excess or surplussolder being thus forced out or away from these particular Junctions.Thereby, and with appropriate determination of the applied pressure, aminimum layer or thickness of joining solder consistent with appropriatestrength and with suitable sealing action is achieved while also aminimum interference with departure from true roundness of the ultimatestructure is brought about. In this latter connection it will berecalled that thehalfballs 24 areeach short of being true hemispheres bysubstantially half the thickness of the flange 40 of the ring 48, theflange 40 thus forming a bandlike portion of the ultimate substantiallytrue sphere; with this interrelation of the parts it is thereforedesirable that the layers of solder be not too thick so as not toelongate the hollow ball in the direction of the axis of the ring 38. Ifdesired, compensation for the thicknesses of the layers of solder may bemade by correspondingly thinning down somewhat the flange 38.

At the same time the upper and lower flanges 4 I, 42 (see Figure '7)become united, by the solder, with the inside surfaces, adjacent theequator, of the two half-balls 24, 24, and at this junction or uniontrue coaxial alinement of the two halfballs 24, 24 is achieved and atthe same time additional strength given to the joint. Excess solder canaccumulate in the circumferential angles or corners, as at 68 in Figure8, to any desired extent to insure further sealing and joining action.

The resultant ball structure appears as shown in Figure 12, being now asubstantially true sphere, hollow and thin-walled and light in weightand having projecting about an equator thereof the flange 40 of thesecuring and alining ring 38. That flange too is preferably ofrelatively small thickness and it is now to be removed.

Accordingly, I provide a downwardly movable die member 10 (Figure 12)provided with a recess or seat II that is of a radius of curvature equalto that of the outer surface of a half-ball 24 but of a depth less thanits radius of curvature. lower die or shearing member 12. The latter isillustratively in the form of a fixed hollow cylinder or sleeve whoseinside cylindrical surface has a diameter or radius of curvature equalto those of the ultimate ball structure, illustratively 0.500 inch. Itsupper edge is a cutting edge which is toothed as at 12 to provide aplurality of individual cutting edges 12*, 12 etc, illustratively four,five or six in number, that are inclined to the horizontal by, forexample 45. With part 70 raised, a ball is now-rested on the lowermember 12 with the flange 40 resting upon the apices of the plurality ofcutting teeth, the lower half of the ball extending into the hole ofmember 12. Member 10 now moves downwardly, engages the upper half of theball structure, and forces it downwardly, whereby the flange 40, eventhough of relatively thin stock, is progressively sheared at four, fiveor six (as the case may be) different points and, moreover, pointsuniformly distributed throughout the circle of the flange. Thereby, riskof crushing the upper half-ball member 24 or of distorting it or otherparts of the soldered assemblage, is dependably avoided and,furthermore, the risk of disrupting the soldered joints substantiallyeliminated. The resultant hollow ball is discharged through the lowerend of the hole in part 12 and then appears Below the die member 10 ismounted a' as shown in Figure 13 from which it will be seen that theexternal surface of the hollow ball is made up of really three zones ofwhich the middle one is a narrow equatorial zone represented by theouter surface of the sheared thin flange 40.

The resultant hollow ball structure may now be "flnished in anysuitablemanner, that is, as to its surfacing. For example, it may now be tumbledwith a suitable tumbling or abrasive compound, after which it may evenbe ground in a grinding machine or other suitable grinding apparatus, itbeing noted that, though hollow and light in weight, it has suflicientstrength and rigidity to withstand the removal of some metal by grindingwhere, as may be desired under certain circumstances, greater precisionmay be desired. After tumbling and/0r grinding, it may be burnished andthen, preferably, it is electroplated with a suitable metal,illustratively tin, for rea sons earlier above pointed out. In Figure 14the ball is shown after the completion of the tinplating and at 15 isindicated, somewhat exaggerated, the outer coating of tin. The lattermay be of a thickness appropriate to-the particular use to which theball is put and for usual types of whiskeys and gins, a tinplating ofslightly under 0.001 inch in thickness will sufiice.

The shearing step indicated in Figure 12 and above described not onlyshears off the surface or projecting portions of the flange 40 but alsocleans off surplus solder that might be accumulated during the solderingoperation and also smooths oif and virtually merges together theexternal surfaces of the three parts that-make up the ball. This andsubsequent steps, where the latter areemployed, insures the provision ofa smooth, clean, substantially spherical surface, free from protrusionsor projections, onto which the plated coating 15 of Figure 14 is laiddown. The latter, moreover, also forms a continuous and non-porousenvelope for encasin'g the ball, gives double security against leakageof liquid into the ball, and also gives the ball a neat, clean, andsmooth external surface.

The weight of the ba1l, utilizing the illustrative dimensions abovegiven, will be found to be between 13.5 and 15 grains, thus meeting theratio above outlined and in general meeting all of the requirements andcharacteristics above set forth in detail. It may be noted that, in agiven run of production, I prefer to use the step of grinding, describedabove, or other means of abrading, of the ball construction prior toplating to bring about, where necessary, a sufilcient reduction inweight to give the ultimate construction, that is, after plating, thedesired factor of weight.

It will thus be seen that there has been provided in this invention aball construction and method and apparatus for making it in which thevarious objects hereinbefore noted, together with many thoroughlypractical advantages are successfully achieved.

As many possible embodiments may be made of the mechanical features ofthe above invention and as the art herein described might be varied invarious parts, all without departing from the scope of the invention, itis to be understood that all matter hereinbefore set forth, or shown inthe accompanying drawings is to be interpreted as illustrative and notin a limiting sense.

I claim:

1. In a method of hollow metal ball constructionQthe steps whichcomprise forming out of sheet metal two shells each slightly less than atrue hemisphere, forming a cylindrical band of an outside diameter suchthat its ends are receivable into the open ends of said shells and withan outwardly projecting centrally positioned flange of a thicknesssubstantially equal to that by which said two shells lack being a truesphere,

applying solder to said band member, assembling the latterto saidtwoshells with the end edges of the latter contacting said flange and withsaid cylindrical band portion alining said two shells coaxially, andheating the resultant assemblage to cause flow of the solder and unionthereby of the two parts.

2. In a method of hollow metal ball construction, the steps whichcomprise forming out of sheet metal two shells each slightly less than atrue hemisphere, forming a cylindrical band of an outside diameter suchthat its ends are receivable into the open ends of said shells and withan outwardly projecting centrally positioned flange of a thicknesssubstantially equalto that by which said two shells lack being a truesphere, applying solder to'said band member, assembling the latter tosaid two shells with the end edges of the latter contacting said flangeand the said cylindrical band portion alining said two shells coaxially,heating the assembled parts to cause flow of the solder while pressingthe two shells toward each other and hence against said flange, and thencooling the assemblage to freeze the solder.

3. In a method of hollow metal ball construction, the steps whichcomprise forming out of sheet metal two shells each slightly less than atrue hemisphere, forming a cylindrical band of an outside diameter suchthat its ends are receivable into the open ends of said shells and withan outwardly projecting centrally positioned flange of a thicknesssubstantially equal to that by which said two shells lack being a truesphere, assembling said two shells and said band with the ends of theletter received respectively into the open ends of said shells and withthe edges of the latter abutting said flange, and sealing the junctionstherebetween.

4. In a method of hollow metal ball construction, the steps whichcomprise forming out of sheet metal two shells each slightly less than atrue hemisphere, forming a cylindrical band of an outside diameter suchthat its ends are receivable into the open ends of said shells and withan outwardly projecting centrally positioned flange of a thicknesssubstantially equal to that by which said two shells lack being a truesphere, and soldering said two shells and band together with the ends ofthe latter received respectively intothe ends of said shells.

5. In a method of hollow metal ball construction, the steps whichcomprise pressing together two sheet metal substantially hemisphericalshells with a cylindrical band having its ends received into theotherwise open ends of said shells and having laterally projecting meansfor engagement with the peripheral edge of at least one of said shellswhereby the aforesaid pressing together of the parts is prevented fromtilting the band and the ends of the latter are maintained in alinementrespectively with the otherwise open ends of said shells, adjacentcontacting surfaces having solder applied thereto, and heating the partswhile being pressed together to cause flow of the solder, and thencooling the parts.

, 6. In a method of hollow metal ball construction, the steps whichcomprise pressing together two sheet metal substantially hemisphericalshells with a cylindrical band having its ends received into theotherwise open ends of said shells, and applying a pressure sufllcientto cause the end edges of said shells to abut against an outwardlyprojecting flange on said band, and heating the resultant assemblagewhile still pressed together to cause flow of solder to take place atadjacent contacting surfaces of the parts, and then cooling theassemblage.

7. The steps as claimed in claim 6 to which is added the step oftrimming oil. the outwardly projecting flange to an outside diametersubstantially equal to that of said hemispherical shells.

8. The steps as claimed in claim 6 to which are added the steps ofsevering those portions of said outwardly projecting flange that extendbeyond the outside radius of said shells, and plating a metal coating onthe exterior surface of the resultant hollow ball.

9. In a method of hollow metal ball construction, the steps whichcomprise pressing together two sheet metal substantially hemisphericalshells with a cylindrical band having its ends received into theotherwise open ends of said shells, adjacent contacting surfaces havingsolder applied thereto, heating the parts while being pressed togetherto cause flow of the solder, and then cooling the parts, abrading theexternal surface of the resultant hollow ball, and depositing a metalcoating over the external surface thereof.

10. In a method of metal hollow ball construction, the steps whichcomprise securing together two substantially hemispherical sheet metalshells and an intermediate alining member in the form of a cylindricalband having its ends respectively received within the ends of saidshells and having an outwardly projecting flange, resting the resultantassemblage in a die seat of less than hemispherical extent and receivingtherein the major portion of one of said shell parts, thereby to sustainthe sheet metal of the latter against deformation, and shearing off thelaterally projecting portions of said projecting flange.

11. In a method of metal hollow ball construction, the steps whichcomprise securing together two substantially hemispherical sheet metalshells and an intermediate alining member in the form of a cylindricalband having its ends respectively received within the ends of saidshells and having an outwardly projecting flange, resting the resultantassemblage in a die seat of less than hemispherical extent and receivingtherein the major portion of one of said shell parts, thereby to sustainthe sheet metal of the latter against defor- 55 -mation, andprogressively shearing ofl, in a plurality of increments distributedabout the periphery of the flange, the portion of the latter projectingbeyond the radius of said shell parts.

12. In a method of metal hollow ball construction, the stepswhich'comprise securing together two substantially hemispherical sheetmetal shells and an intermediate alining member in the form of acylindrical band having its ends respectively received within the endsof said shells and having an outwardly projecting flange, and removingthose portions of said flange that extend beyond a sphere whose radiusis the same as that of said hemispherical shells.

13. A hollow metal ball comprising, in combination, two sheet metalshells each slightly less than a true hemisphere and an alining andconnecting member therefor, said member comprising a cylindrical band-ofan outside diameter such that its ends are receivable into the open endsof said shells for thereby alining the latter and bringing their axesinto coincidence, said band having an outwardly projecting substantiallycentrally positioned flange of a thickness substantially equal to thatby which said two shells lack being a true sphere, said flange beingpositioned between the end edges of said shells and having an outsideradius equal to the radius of said hemispherical shells.

14. A hollow metal ball comprising two substantially hemisphericalshells with means alining them coaxially and securing them together andsealing the junction therebetween, said means comprising a band-likemember having portions projecting respectively into said two shells andin engagement with interior surfaces of the latter, said member havingoutwardly projecting means for engagement with edge portions of at leastone of said shells to prevent tilting of said bandlike member and saidone shell out of coaxial relationship.

15. A sub-assembly hollow ball construction comprising two substantiallyhemispherical shells respectively received over the ends of a securingand alining member, the latter having outwardly projecting meansinterengaging with edge portions of at least one of said shells forpreventing tilting of said member.

16. A sub-assembly hollow ball construction comprising two substantiallyhemispherical shells respectively interfltted with the ends of acylindrical band-like member that has an outwardly projecting flangethat is interposed between the end edges of said two shells, said flangebeing of a radius greater than the radius of said shells.

17. A hollow metal ball construction comprising, in combination, twosheet metal substantially hemispherical shells of small thickness havingreceived within their ends and being thereby alined a band-like memberwhose outside radius is substantially equal to the inside radiusof saidshells, said shells and said band member being soldered together, and anelectro-deposited metal coating over the external surface of theresultant hollow ball for insuring the sealing of the soldered jointsbetween said shells and band member;

18. A hollow metal ball comprising three sheet metal parts whoseexternal surfaces are respective segments of a spherical surface of thesame radius, two of which parts are cap-like members and the third beingan intermediate band-like spherical sectional member, said membershaving means whereby they are interfitted and when interfltted make up asubstantially true hollow sheet metal sphere.

KNUD KNUDSEN.

